Automotive muffler



Aug. 29, 1961 w. H. POWERS 2,998,093

AUTOMOTIVE MUFFLER Filed April 1, 1955 1N VEN TOR.

Taf? AIX/S1 States 2,998,093 AUTOMOTIVE MUFFLER Walter H. Powers, Jackson, Mich., assignor, by mesne assignments, to Walker Manufacturing Company, Racine, Wis., a 'corporation of Delaware Filed Apr. 1, 1955, Ser. No. 498,639 `7 Claims. (Cl. 181-54) This invention relates to muers and, in particular, to muilers for silencing the exhaust noise of automotive internal combustion engines.

It is the principal object of this invention to provide a muilier which is highly effective in silencing the exhaust noises of automobiles and yet may be readily manufactured at a low cost while being extremely sturdy and durable in construction.

The invention accomplishes this and other objects by means of a construction in which the various gas passages within the muler casing are provided in a pair of stampings which are secured together. Th stampings, commonly referred to as pancakes in the field, are secured to transverse partitions within the muler casing. The inlet and outlet bushings are spot Welded to the partitions, to the pancake, and to the end heads of the mulers. As a result of this arrangement the various parts are rigidly interconnected and an extremely strong, durable construction resistant to leaks and blowouts is obtained.

In order to illustrate the principles of the invention a preferred embodiment thereof is shown in the accompanying drawings in which:

FIGURE 1 is a longitudinal section through a muier embodying the invention;

FIG. 2 is an elevation taken at the inlet end of the mufiier; and

FIG. 3 is a cross section taken along the line 3-3 of FIG. 1.

The muer 1 has an oval sheet metal casing 3 of conventional construction, the parts therein also being formed of conventional materials, normally low carbon steel. The casing 3 is closed at the inlet end by a header 5 and at the outlet end by a header 7, both headers being interlocked with the metal of the casing 3 as shown by the joints 9. Within the volume of the casing 3 is an inlet partition 11 which extends transversely of the length of the muffler and which has an outer or peripheral flange that is Spot welded to the casing 3 as shown at 15. There is another transverse partition 17 adjacent the outlet end of the mufer and this has a peripheral ange 19 that is spot welded at 21 to the casing 3. The inlet header 5 and the inlet partition 11 have aligned necks 23 and 25, respectively, formed by the anges that extend toward the outside or outwardly of the muer. Similarly, the outlet header '7 and the outlet partition 17 have aligned necks 27 and 29 formed by flanges extending toward the outlet end of the muiier casing 3. An inlet bushing 30 extends through the aligned necks 23 and 25 and is spot welded thereto as shown, respectively, by the reference numerals 31 and 33. In order to permit this assembly to be made the bushing 30 is expanded by a suitable expanding tool at 35 into tight contact with the neck 31 so that spot welding can occur after the header has been attached to the casing 3 and the internal parts assembled inside of the casing 3. The outlet bushing 36 is attached in a similar manner to the aligned necks 27 and 29, the bushing being spot welded at 37 to the neck 29 and expanded at 39 into'contact with the neck 27 after all the parts have been assembled and then the ange 27 spot welded at 41 to the expanded part of the bushing 36.

Located between the two partitions 111 and 17 are a pair of complemental stampings 43 and 45 which deine the gas passages through the volume of the casing 3. As will be clear from a consideration of FIGS. 1 and 3,

the stampings 43 and 45 have parallel longitudinally extending semicircular troughs 47, 49 and 51 pressed therein and when the stampings 43 and 45 are placed together, these troughs cooperate to define the gas passages 53, 55 and 57. There are flanges on the outside edges of the stampings 43 and 45 as shown at 54 and these are spot welded along with the webs 56 and 59 between the outer gas passages 53 and 57 and the inner gas passage 55. The stampings 43 and 45 are shaped so that the gas passages project a slight distance beyond the edges of the webs as will be seen most clearly in FG. l. The projecting portion of the gas passage 53 at the inlet end of the muffler ts into a neck or ilange 6@ in the partition 11 and is spot welded to it. Likewise, the projecting portion of the gas passage 57 at the inlet end tits in a ange 61 in the inlet partition 11 and is spot Welded to it. The projecting end of the center gas passage 55 tits within the inlet bushing 30 and is spot welded to it as shown at 63. at the outlet end of the muer the projecting portion of the gas passage 53 lits within the outlet bushing 36 and is spot welded to it as shown at 65. The projecting end of the gas passage 57 lits into a neck or outturned flange 67 in the outlet partition 17 and is spot welded to it as shown at Sil. At the outlet end of the muiiler the gas passage 55 is cut o3 as shown by the cutout 69. rl`he inlet partition 11 has four small openings '71 formed therein and one larger opening 73 and these communicate the chamber 75 between the partitions 11 and 17 with the chamber 77 between the partition 11 and the inlet header S. The partition 17 has no openings, that is, it is imperforate except for the openings provided by the necks 29 and 67.

It will be appreciated that the pancake construction, the partition, and the inlet and outlet bushings 3l] and 36 can be preassembled as a spot welded subassembly and then inserted as a unit through an end of the casing 3 after which the partitions can be spot welded to the casing and headers 5 and 7 put in place and interlocked at 9. Since the bushings 30 and 36 are expanded at 35 and 39 into a tight (good spot weld) tit, the openings 23 and 27 can be substantially oversize, thus facilitating manufacturing and assembly by reducing the criticality of dimensions.

Turning now to the operation of the mutlier, it will be seen that gas entering at the inlet nipple 30 will ow longitudinally through the gas passage 55 until it comes to the cross-over opening 69. Slots 79 or other openings formed in the troughs 49 provide transverse outlets for gas ilowing through the passage 55. The gas owing out of the openings 79 or out of the end of the passage 55 into the cross-over 69 enters the chamber 75 and since the partition 17 is imperforate the gas reverses its direction of How and flows backwardly toward the inlet partition 11. The openings 71 and 73 in the partition 11 permit the gas in the chamber 75 to pass into the chamber 7'7 without substantial back pressure. The gas and sound waves in chamber 77 then can ilow through the outlet passage 53 and through the outlet bushing 36 to the tail pipe of the automobile and thence to atmosphere. The outlet passage 53 has transverse slots or other suitable openings i9 formed in the troughs 47 and this permits by-pass ilow of gas between the passage 53 and the chamber 75. Also communicating with the gas and sound waves in the chamber 77 is the imperforate gas passage 57 which empties into a tuning or resonator chamber 83 formed between the partition 17 and the outlet header 7. The gas passage 57 forms the only inlet and outlet to the chamber 83.

It will now be seen that the invention provides an economically constructed but durable and rugged mutler structure. While various modifications can be made without departing from the spirit and scope of the invention, the structure illustrated has been found to produce particularly satisfactory results intended in particular for use on six cylinder inline engines with fluid torque converters, the chambers 75 and 83 serving to .control and eliminate the sustained heavy power note accompanying the use of iiuid torque converters, The .Chevrolet with Power Glide is a specic example Vof a car that could be mumed by means of the present construction.

I claim:

1. A muiiier construction comprising a casing, inlet and outlet headers secured to the casing and closing the ends thereof, partitions spaced from each other and located within said casing and rigidly spot-welded thereto, an inlet bushing rigidly spot-welded to said inlet header and to the adjacent internal partition, an .outlet bushing rigidly spot-welded to the outlet header and the adjacent inner partition, said bushings acting to transmit load on the headers to said partitions, and a pair of complemental stampings spot welded together and deiining a plurality of gas passages connecting the inlet bushing to the outlet bushing, said stampings being spot welded to both said partitions and to the inlet and outlet bushings.

2. in a muffler construction, an oval shaped sheet metal casing, an inlet header interlocked with the casing to close one end thereof, an outlet header interlocked with the other end of the casing to close the end thereof, a transverse inlet partition within said casing and spot Welded thereto, a transverse outlet partition within said casing and spot welded thereto and spaced longitudinally from said inlet partition, said inlet header and inlet partition having aligned openings with flanges extending outwardly thereof, said outlet header and partition also having aligned openings with flanges extending outwardly thereof, an inlet bushing seated in the ilanged openings in said inlet header and inlet partition and spot welded to both said anges, an outlet bushing in said openings in the outlet header and outlet partition and spot welded to both the flanges thereof, a pair of complemental sheet metal stampings contoured to t the shape of said oval-shaped casing and spot welded together, said pair of stampings being provided with troughs interconnected by web portions that cooperate to dene three parallel passages opening out `of opposite ends of the assembly of stampings, two of said passages formed in said stampings projecting beyond the web portions of the stampings and being tted in flanged openings in the inlet and outlet Lpartitions and spot welded thereto, one of said passages constituting an inlet passage and tting in said inlet bushing and being spot welded thereto, the other of said passages constituting an outlet passage and being tted in said outlet bushing and spot welded thereto, said stampings being cut out so that the inlet passage terminates inwardly of said outlet partition and empties into a chamber defined by said casing between said inlet and outlet partitions `and serving to ernpty inlet vgas into said chamber, said inlet partition having relatively large openings therein to cornmunicate said chamber with a chamber formed between the inlet header and the inlet partition, said outlet partition being imperforate except for said gas passage openings, the other of said gas passages serving to connect the chamber between the inlet partition and the inlet header with the chamber between the outlet header and the outlet partition.

3. In a muiher construction, a casing having an inlet and an outlet header, rst and second transverse partitions inside of said casing and cooperating with said headers to define a first chamber between saidinlet header and said Iirst partition and a second chamber between said outlet header and said second partition, a pancake gas passage construction extending between said partitions and supported at opposite ends by them, said pancake construction providing iirst, second, and third parallel gas passages, said first passage being directly connected to an inlet in said inlet header and emptying into a third chamber comprising the volume of said casing between said rst and second partitions, said second -passage being directly connected to an outlet in said outlet header and receiving gases from said first chamber, said iirst partition having openings connecting said third and said iirst chambers so that said volume comprises a ilow pas- Sage for gas iiowing from the first to the second passages, said second partition being imperforate except for an opening receiving said third gas passage, said third gas passage interconnecting said first and said second chambers.

4. The invention set forth in claim 3 wherein said pancake construction is provided with apertures that form louvers in the rst and second gas passages, the third gas passage being irnperforate.

5. The invention set forth in claim 3 wherein said pancake construction is formed so that said rst passage terminates inwardly of the ends of the rst and third passages and at an intermediate point in said third chamber.

6. In a mufer construction, a casing, a spot Welded subassembly unit inside the casing comprising transverse partitions with inlet and outlet bushings spot welded thereto and a pancake gas passage construction extending between the partitions and spot welded at its ends thereto and to said bushings, headers closing the ends of the casing and interlocked therewith and having openings through which the bushings extend and outwardly extending flanges .around said openings, said flanges being of greater diameter than all of the length of the respective bushing extending therethrough except that portion of the bushing registering therewith, said registering bushing portions being expanded into a tight ht with said flanges, and spot welds securing the flanges and registering portions together.

7. In a muiiier construction having a casing with an inlet and an outlet, a pair of transverse partitions inside of said casing, a pancake gas passage construction extending between and secured at opposite ends to said partitions, said pancake comprising a pair of complemental sheet Ymetal stampings spot welded together and defining a plurality of parallel and substantially co-extensive gas passages, one of said passages being directly connected at one end to said inlet, another of said passages being directly lconnected at one end to said outlet, said one ends of said respective passages being Vrespectively at the opposite longitudinal ends thereof, and means providing for gas flow between the other ends of said gas passages comprising a large cutout portion in said pancake adjacent one partition and between said partitions, the other of said partitions having a large opening therein, the volume of the casing between said partitions and outside of said other partition comprising a flow passage connecting said other ends of said gas passages.

References Cited in the tile of this patent UNITED STATES PATENTS 2,109,220 Noblitt Feb. 22, 1938 2,235,705 Haas Mar. 18, 1941 2,652,128 Cary Sept. 15, 1953 FOREIGN PATENTS 109,785 Australia Feb. 9, 1940 

